hello!

Well Im in work experience at the moment from college and im working at a university for two weeks.

Im working with the technicians as a computer admin/techie and he starts rambling about virtualization and i had absolutely no idea what he was talking about so he explained.

Sometimes you want a server to run more than one service, maybe an application server that serves each station the applications it needs and controls them and it also needs to run an email service. On a large network running both of these services on one server can cause massive lag and huge problems with possibly 50 requests for 5 or 6 different applications and then another 40-50 for emails and then also of course running an internet connection and security things like firewalls. Thats quite a lot for one server and in somewhere like a university where you might have 500-600 computers you could have at any one time 400+ requests for applications and 400 for email so you see the problem. The old solution was to run one server for each and every service, so one for applications and one for email etcetera. When you consider the prices for a decent server to be able to deal with atleast 400 requests and you would need possible 4 or 5 of these for different departments and services it just gets ridiculous. So what do you do?

Well you can perform virtualization. This is when you take one machine, eg a server, and create a virtual machine inside this machine. So for a start you have the hardware obviously you cant just create new hardware but that doesnt matter because the virtual machines act like they have their own hardware when in fact they share it. The server is now the host containing the host operating system etcetera. Inside the server is also the guest machine which is the new "virtual machine" This machine is almost like an emulation, it acts like a whole new machine, it is allocated its own RAM which only it can use, the other host machine uses its own ram too so theres no problems with that. They both use the same hard drive, the host machine uses the whole hard drive and guest machine uses a file which inside contains directory information etcetea, similar to an image of a hard drive. When the guest operating system is started it begins using the virtual hard drive file (dont ask me how i have no idea but it does!) and then is uses its allocated RAM for its own use. It also shares all the other hardware of the host machine unless you tell it not of course.


so in summary the virtual machine is now litereally that, a virtual machine, it uses exsisting hardware as told to do so by you and it runs as a totally idependant system, on it you can have ANY operating system and software as long as it can be supported by hte hardware, (like dont run vista on 16mb of RAM ) So now instead of having 3 servers you simply by one good server and add two virtual machines thus making 3 machines in total. Now each machine can run its own services, so the host could run applications, the first guest could run email and the second guest machine can run security and other services.

So how can YOU do this? well any computer can do it so long as you have good enough hardware, id suggest atleast 512mb RAM then each virtual machine can have 256mb RAM and if you plan on actually using them for working etcetera then atleast 40gb hard drive as it will have atleast two operating systems and sets of applications. Nothing else is really important, just make sure the hardware you use is compatible with the software you plan on using. Then you will need a virtualization software, i have used two on work experience called VMWare (google it, its near the top) and Windows Virtual PC (again google it) Both unfortunately are trial softare but it gives you an idea, i have no doubt that there are free alternatives out there so if you plan on using this for more than about 4 weeks download a free version of pay for one of the above.

From what ive seen and used ( VMware on XP home as host and running vista beta 2 as guest, and Windows Virtual PC on XP pro as host and running vista beta 2 as guest) i will definately say use VMWare, Windows Virtual PC does NOT run on XP home which is what a lot of home users use, Also with vista it was so slow and laggy and crashed a few times, not to mention the trouble with drivers and long satart up and shut down times of the guest (vista) although the host (xp PRO ) was very responsive and acted as normal. With VMWare Vista ran alot smother and alot faster and much more usable, it also was much better with the video drivers and i think auto detected them. It was also able to use an ISO image to install vista from where as Virtual PC needed us to download a CD drive emulator.

Its an extremely usefull thing if you are a software developer to see how your product runs on different versions of windows or different distro's of linux/unix or even on mac as you can run any operating system as a guest without fear of damaging the system or needing to uninstall anything if all goes to pot, just simply delete the virtual machine using the software. Its also very usefull for server application like i said already. or if working on a shared machine and you want to run another operating system without changing things for other people.

downsides: well you need a decent system spec to be able to use both machines at the same time with a reasonable responsiveness and stability. so 512mb RAM and 40gb hard drive. Other than that all is good, if something goes wrong it wont affect both machines and you can easilly just delete the virtual machine and remake it again.

I suggest you all to check it out if you like to use windows and linux/unix/mac as it wont damage the windows partitions and if something doesnt work in another operating system you can easilly use that function in the other operating system without restarting.

Farewell

Wow that was very interesting. I did not know that was called virtualization. I thought maybe it was going to be about Virtual worlds which were popular in the late 90s and early in this new century. I learned a little bit more today. I have a duel booting machine with windows and linux but its not always easy. I used differant hardrives for my operating systems cause I have them.

Great Explanation. I am happy that I learnt a new Jargon. This is the reason I like Trap. Keep it up dude.

This virualisation is being used in the Linux with a software named wine to run Windows applications like Microsoft Office in Linux.